Gastric bypass/bariatric surgery

Description
Bariatric surgery is gastrointestinal surgery for obesity.

Purpose/indications
Obesity is often defined with a mathematical formula called body mass index (BMI), which expresses a person's weight-to-height ratio. In fact, BMI is considered to be one of the best indicators of body fat.
BMI is calculated by dividing your body weight in kilograms by the square of your height in meters. A BMI of 30 or higher is considered obese. A BMI higher than 40 is considered severely obese, which on average means about 100 pounds overweight for men and 80 pounds overweight for women.

Bariatric surgery may be appropriate for people who have a BMI of 40 or higher and are not able to lose weight through traditional methods. It may also be appropriate for those who have a BMI of 35 or higher and obesity-related health problems, such as heart disease, diabetes, high blood pressure or obstructive sleep apnea.


Patient preparation
Your doctor will ask questions about your medical history and do a physical exam. Preoperative lab tests may include a complete blood count, chemistry panel, urinalysis and blood typing. You'll also need a chest X-ray and electrocardiogram (ECG, a recording of the electrical activity of the heart). You may also need other tests depending on your health history, such as a gallbladder evaluation.

Procedure
Although every surgery has its own standard procedure, your individual health history could play a role in any variation to the procedure. Discuss these issues with your doctor.
There are two basic bariatric surgeries: restrictive and malabsorptive. Restrictive bariatric surgery limits the amount of food you can eat at one time and delays the emptying of food from the stomach. This gives you a feeling of fullness after eating a small amount of food. Malabsorptive procedures restrict the amount of calories and nutrients your body absorbs. Various surgical procedures may use either one or a combination of these methods. These procedures are often done with minimally invasive surgical techniques using a laparoscope (a thin tube equipped with a camera lens and light) and small incisions. Be sure to ask your doctor for details.

Restrictive

Vertical banded gastroplasty (VBG) is a restrictive procedure in which staples and a band are used to create a small pouch at the top of the stomach. VBG is currently the most common restrictive surgery.

Adjustable gastric banding (AGB) is another restrictive procedure in which a band is used to create a small pouch at the top of the stomach. The band can be tightened or loosened through the injection of a salt solution into a reservoir placed under the skin.

Benefits
About 80 percent of people who undergo restrictive surgery lose weight -- on average, 25 percent of the preoperative weight. About 30 percent of people who undergo restrictive surgery eventually reach a normal weight. If the procedure is done with a laparoscope, you'll have a lower risk of complications, less pain and a shorter recovery time.

Risks
Restrictive techniques are less effective for maintaining long-term weight loss than malabsorptive procedures. A common side effect of restrictive surgery is vomiting, often caused by eating too much food at once or not chewing food well enough. With VBG, the band may wear away or the staple line may break down. With AGB, the band may slip, leak or erode. Rarely, an infection or blood clots may develop. A rare complication such as pulmonary embolus (an abnormal particle, such as an air bubble or blood clot, circulating in the lung) may be fatal.

Malabsorptive

Roux-en-Y gastric bypass (RGB) is a technique that combines both restrictive and malabsorptive methods. Like the restrictive surgeries, a small pouch is created at the top of stomach. In addition, a Y-shaped portion of the small intestine is attached to the stomach pouch. This causes food to bypass the lower portion of the stomach, as well as the first and second portions of the small intestine (the duodenum and the jejunum). As a result, the body takes in fewer calories and nutrients, leading to weight loss.

Biliopancreatic diversion (BPD) is a complex procedure that involves removing portions of the stomach. The stomach pouch that remains is connected directly to the last portion of the small intestine, bypassing the duodenum and jejunum. This surgery is usually reserved for people who have a BMI of 50 or higher.

Benefits
Malabsorptive techniques are more effective for maintaining long-term weight loss than restrictive surgeries. They also result in greater weight loss and improvement of obesity-related conditions, such as high blood pressure and diabetes. The average weight loss for bypass procedures is 30 percent of the preoperative weight. If the procedure is done with a laparoscope, you'll have a lower risk of complications, less pain and a shorter recovery time.

Risks
A condition known as "dumping syndrome" is a common problem after malabsorptive surgery. It occurs when food moves too rapidly through the small intestine, causing nausea, sweating, faintness and diarrhea. Other side effects may include dairy intolerance, constipation, headaches, hair loss, a hernia (protrusion) at the incision site and depression.

Malabsorptive techniques may lead to nutritional deficiencies, such as lack of iron or calcium. (These nutrients are typically absorbed by the portions of the small intestine that are bypassed during the surgery.) Supplements are often needed to prevent osteoporosis and other complications of decreased calcium or iron absorption. People who have undergone a BPD must take vitamin A, D, E and K supplements as well.

Rarely, an infection or blood clots may develop. A rare complication such as pulmonary embolus (an abnormal particle, such as an air bubble or blood clot, circulating in the lung) may be fatal.


Postprocedure care
Up to 40 percent of people who undergo bariatric surgery are monitored in an intensive care unit for one to two days after surgery, especially those who have a history of heart or respiratory conditions. Supplemental oxygen may be needed for the first few days to prevent hypoxemia (low blood levels of oxygen). Your postoperative care will depend on the surgical approach used in your procedure. Minimally invasive techniques have a shorter recovery time. Again, ask your doctor for details.
After surgery, the typical diet begins with sips of water, advancing to pureed foods as tolerated. The pureed diet is recommended for two to four weeks, which gives you time to adjust to eating less food and decrease the risk of vomiting. You'll eat soft foods next, and finally resume a regular diet. Your doctor may recommend consulting a nutritionist to help you plan a balanced diet and learn modified eating behaviors to reduce the risk of nausea and vomiting. You'll also learn whether nutritional supplements are needed to prevent vitamin or mineral deficiencies.


Considerations
Generally, bariatric surgery is not recommended for pregnant women and people who have:
active substance abuse
active peptic ulcer disease
cancer
end-stage renal disease
symptomatic coronary artery disease
certain psychiatric illnesses
Large amounts of weight may be lost rapidly after successful bariatric surgery. This may increase the risk of developing gallstones for people who still have their gallbladders. Some doctors may recommend a cholecystectomy (removal of the gallbladder) at the same time as the bariatric surgery to prevent potential gallstone problems after surgery. Hepatitis (inflammation of the liver) is another risk after rapid weight loss.


Pregnancy-specific information
Again, bariatric surgery is not recommended during pregnancy. Women who want to become pregnant after surgery are encouraged to wait until their weight has stabilized, due to the potential nutritional deficiencies that often accompany rapid weight loss.

Senior-specific information
In the past, adults older than age 50 were not considered eligible for bariatric surgery due to higher postoperative death rates. With improvement in surgical techniques and management, however, age is no longer considered a contraindication to surgery. If you're over 50 and believe you're a candidate for this type of surgery, consult your doctor for details.